Sunday, August 4, 2013

Starting to Plan the Body of Butler

I've started doing some research on how I want Butler to look and putting down measurements on what I find as I work.

I chose to do a dual track system on the bottom similar to "Wall-E". The belt will be 3" wide. I chose to go with lynxmotion's parts. They have a good reputation and durable. After doing some calculations, the motors will need to be doing 292RPM for the 3" diameter sprockets that'll be used for the tracks on the bottom of the body. The equation is RPM = (( 60 * speed ) / ( diameter * PI )).

The speed remember is how many inches you want to go per second, in/s. I did some calculations and found out that a human walking averages 45in/s. What I did is laid out a tape measurer and walked normally the length of the tape measurer. I had a small tape measurer at the time of 138" and I was able to walk it in 3.1 seconds. You get 44.5" when you do the math. So I just averaged it to 45" to make it easier. The diameter is the size in inches of how big the wheel or sprocket attached to the motor. In my case, it's 3".

I've chose to go with this motor times two for the track system. Planetary Gear Motor - 12vdc 20:1 300rpm (6mm shaft) It's got the speed I need. Now, the plan is to keep Butler light and strong so as soon as weight is added onto these motors, the RPMs will drop and hopefully just to the right number that I've proposed above. That's why I chose to do a little bit of a higher RPM'd motor.

Here's a sketch of what I have planned. My goal is to come as close to this as possible. The box I already have on hand and uploaded it in my first post.